For \(\bar{B^0} \rightarrow \bar{K^{*0}}(\rightarrow K^-\pi ^+)\ell ^+\ell ^-\)  decay, \(\theta _{K}\)  is the angle between the directions of kaon in the \(\bar{K^{*0}}\)  rest frame and the \(\bar{K^{*0}}\)  in the rest frame of \(\bar{B}\) . The angle \(\theta _{\ell }\)  is between the directions of the \(\ell ^-\)  in the dilepton rest frame and the dilepton in the rest frame of \(\bar{B}\)  whereas the angle \(\phi \)  is the azimuthal angle between the plane containing the dilepton pair and the plane encompassing the kaon and pion from the \(\bar{K^{*0}}\) . For \(B^0 \rightarrow K^{*0}(\rightarrow K^+\pi ^-)\ell ^+\ell ^-\)  decay mode, \(\theta _{K}\)  is the angle between the directions of kaon in the \({K^{*0}}\)  rest frame and the \({K^{*0}}\)  in the rest frame of \({B}\)  whereas the angle \(\theta _{\ell }\)  is between the directions of the \(\ell ^+\)  in the dilepton rest frame and the dilepton in the rest frame of \({B}\) .
This leads to the following transformation of angular coefficients under \(CP\)  [1]}
\(I^{(a)}_{1,2,3,4,5,6} \Longrightarrow \bar{I}^{(a)}_{1,2,3,4,5,6}, \quad I^{(a)}_{7,8,9} \Longrightarrow -\bar{I}^{(a)}_{7,8,9},\) 
